Suppose we were comparing the mean age of buyers of new domestic cars to the mean age of buyers of new imported cars.

What is the variable under consideration?
A. buyers of imported cars
B. buyers of domestic cars
C. age of buyers
D. None of the above

What are the two populations under consideration?
A. buyers of new domestic cars and buyers of new imported cars
B. age of buyers of new domestic cars and age of buyers of new imported cars
C. cars and buyers
D. None of the above